Mar

22

Groundbreaking research undertaken by a group headed by Dr. Guy Bloch of the Alexander Silberman Institute of Life Sciences at the Hebrew University of Jerusalem has found that the molecular structure of the biological clock of the honey bee is more similar to the biological clock of mammals than to that of flies.

The research identified and characterized the key genes involved in the biological clock of bees. The findings of the research were published on Oct. 26 in an article describing the honey bee genome sequence in Nature and in a companion paper in Genome Research.

The biological clock is an internal system in the bodies of living creatures that creates circadian rhythms, derived from the Latin expression circa dies that means “about one day.” The critical role of the circadian clock stems from its influence on many processes, such as time of alertness and fatigue, activity rhythms, cyclic changes in body temperature and the secretion of hormones.

The research of Dr. Bloch and his team is part of a worldwide project for mapping the honey bee genome (similar to the human genome project which was completed several years ago). According to Dr. Bloch, “Discovering that molecular characteristics of the biological clock in bees is closer to the biological clock of mammals than that of flies was a big surprise, since previously it had been thought that there is one type of clock that is typical of insects and another typical of mammals. These results change our understanding of the evolution of circadian clocks.”

Dr. Bloch points out that the discovery raises many additional questions concerning the evolution of biological clocks and the significance of differences in the organization of the clock in different creatures. For example, why is the clock of bees closer to humans than that of flies? Is the similarity between bees and mammals related to the behavioral complexity of bees? How did the clock of ancestral insects work: was it more similar to that of bees or flies?

Characterization of the genes in the clock of the bee opens up new directions of research concerning the understanding of the molecular base of complex behaviors, such as sun-compass navigation, time sensing, flexibility in circadian rhythms, and social regulation of the circadian clock. Another reason the research on the evolution and function of clock genes is important is that these genes are involved in a variety of illnesses, such as mental disturbances, alcoholism, problems of overweight and drug addition, as well as in processes relating to aging.

The central biological clock is located in the brain and is made up of groups of “clock cells,” each of which is capable of creating a circadian rhythm independently. These circadian rhythms are generated by complex interactions between “clock genes” that accumulate in the cells and eventually close a cycle of about 24 hours when they shut down their own production. The genes which were isolated by Dr. Bloch and his research team are responsible for this process in bees.

Bees rely on the biological clock for timing visits to flowers when nectar and pollen flow is at its highest. They can learn to reach flowers at nine different points of time during the day within an accuracy of about 20 minutes. The clock is also essential for navigation that uses the sun as a compass because the sun moves during the day from east to west. Bees, whose bodies are slightly longer than one centimeter, precisely navigate to flowers situated as far as 10 km from their beehive.